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HVAC Systems_FA23 > [L3]_Starting HVAC Calculations & Design Conditions > Flashcards

[L3]_Starting HVAC Calculations & Design Conditions Flashcards

1
Q

IND405

Name the six (6) typical internal heat gain (loads) types.

[L3]

A
  1. Fan Energy Loads
  2. Ductwork Energy Transmission & Losses
  3. Light Fixtures
  4. Equipment Motor Loads
  5. Human Sensible & Latent Loads
  6. Plenum area

[L3]

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2
Q

IND405

Per ASHRAE what is the correct weather zone for Long Island, NY?

[L3]

A

Zone (4)

[L3]

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3
Q

IND405

Per ASHRAE which weather zone type is considered Dry?
* Zone (A)
* Zone (B)
* Zone (C)

[L3]

A

Zone B

[L3]

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4
Q

IND405

What is the best direction for a building to face in order to collect the greatest amount of solar irradiance thoughout the day on the northern hemisphere?

[L3]

A

South

[L3]

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5
Q

IND405

Name the state which has the highest temperature and humidity level. Also, define what is occuring at the selected state as well.

[L3]

A
  • State “O”
  • Fresh outside air is being introduced to the AC system during the summer time.

[L3]

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6
Q

IND405

What is the heating/cooling load calculation method required for residential and low-rise applications only?

[L3]

A

Manual J8, created by ACCA (Air-Conditioning Contractors of America)

[L3]

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7
Q

IND405

List the five (5) methods created for building HVAC load calculations.

[L3]

A
  1. Total Equivalent Temperature Difference/Time Average (TETD/TA)
  2. Transfer Function Method (TFM)
  3. Cooling Load Temperature Difference/Cooling Load Factor (CLTD/CLF)
  4. Heat Balance (HB) & Radiant Time Series (RTS)
  5. Manual J8 Method for Residential Applications

[L3]

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8
Q

IND405

Which heating/cooling load calculation method is the most difficult to complete by hand and requires a computer to complete?

[L3]

A

RTS (Radiant Time Series)

[L3]

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9
Q

IND405

W₁ = W₂, expresses what is occuring in an air stream?

[L3]

A

Humidity level remains constant and no additional humidty is added no removed thus only dB is changing on the psychrometric chart.

[L3]

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10
Q

IND405

When cooling & dehumidifiying a space, what change must occur with the temperature?

[L3]

A

The airstream’s temperature must be cooled and brought down below the dew point of the space.

[L3]

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11
Q

IND405

What is the name of the coil labeled (A)?

[L3]

A

Reheat Coil

[L3]

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12
Q

IND405

What does STC stand for?

[L3]

A

Standard Temperature Conditions

[L3]

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13
Q

IND405

What is the STC of dry-air and pressure as defined by ASHRAE?

[L3]

A

68-degrees (F) & 14.7 psia

[L3]

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14
Q

IND405

What is the STC density of dry-air and specific volume as defined by ASHRAE?

[L3]

A
  • Density of Dry-Air @ STC = 0.075 lb/ft³
  • Specific Volume of Dry-Air @ STC = 13.3 ft³/lb

[L3]

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15
Q

IND405

What is the fully expressed equation for Sensible Heat?

[L3]

A

qs = (Qx(60))x(0.075)x(0.24 + (0.45W))xΔt

[L3]

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16
Q

IND405

What is the industries expression for Sensible Heat?

[L3]

A

qs = 1.10xQxΔt

[L3]

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17
Q

IND405

What is the fully expressed equation for Latent Heat?

[L3]

A

qL = [(Q)x(60)x(0.075)x(1076 Btu/lb)]xΔW

[L3]

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18
Q

IND405

What is the industries expression for Latent Heat?

[L3]

A

qL = 4840xQxΔW

[L3]

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19
Q

IND405

Define a SCAV unit.

[L3]

A
  • Self Contained Air-Cooled Vertical Unit
  • A combined condensing unit and AHU which is vertically standing on the floor as one (1) unit in a single location.

[L3]

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20
Q

IND405

What is a single-zone system?

[L3]

A

Simplified systems are dedicated to one (1) area w/o central building controls to satisfy dB temperature w/o significant humidity control.

[L3]

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21
Q

IND405

Which ASHRAE codes dictates IAQ and Ventilation requirements?

[L3]

A

ASHRAE 62.1 & 62.2

[L3]

22
Q

IND405

What are the two (2) types of generic ventilation required for any new project space?

[L3]

A
  1. Natural Ventilation
  2. Mechanical Ventilation

[L3]

23
Q

IND405

Expressed in formulas, list the three (3) scenarios for ventilation.

[L3]

A
  • Scenario #1 - Qsrv = Qor/Xo
  • Scenario #2 - Qsrv = Qsr
  • Scenario #3 - Qsrv = Volume (FT3) * (ACH/60)
  • Scenario #4 - Qsrv = K * (CFM/FT2)

[L3]

24
Q

IND405

What formula is used for the indoor exhaust air is the most important aspect of the design for your space, ie. laboratory?

[L3]

A

Scenario #2

[L3]

25
Q

IND405

What is the name of the HVAC component in this system schematic diagram used to balance the total air-flow?

[L3]

A

Manual Volume Damper

[L3]

26
Q

IND405

List the three (3) types of fire-stopping methods used for HVAC ductwork.

[L3]

A
  1. Motorized Fire Dampers
  2. Spring Loaded Curtain Fire Dampers
  3. Ductwork Fire-Stopping Retaining Angles

[L3]

27
Q

IND405

What is the definition of ASHRAE Standard 55?

[L3]

A

Standard 55 specifies conditions for acceptable thermal environments and comfort zones as is intended for use in design, operation, and other occupied spaces.

[L3]

28
Q

IND405

What is the definition of a Comfort Zone per ASHRAE Standard 55?

[L3]

A

The optimal range/combinations of thermal & personal factors (clothing and activity level) with which at least 80% of the building occupants are expected to express satisfaction.

[L3]

29
Q

IND405

What does SBS stand for and its definition?

[L3]

A
  • Sick Building Syndrome
  • The number of possible health issues or illness generated during the occupancy of a building due to uncomfortable indoor building conditions.

[L3]

30
Q

IND405

List five (5) typical sysmptoms of SBS illness.

[L3]

A
  1. Mucosal Irritation
  2. Asthma
  3. Nose Bleeds
  4. Chest Tightness
  5. Headache

[L3]

31
Q

IND405

What is the defined typical internal core temperature of the standard person per ASHRAE 55?

[L3]

A

98.6°F

[L3]

32
Q

IND405

What is the mean skin temperature of comfort for a typical human per ASHRAE 55?

[L3]

A

88°F to 96.8°F

[L3]

33
Q

IND405

What is the maximum allowed temperature swing before discomfort occurs for a typical person?

[L3]

A

±2.5°F

[L3]

34
Q

IND405

What is the recommended Summer Indoor Design Condition?

[L3]

A

75°F dB & 50% RH

[L3]

35
Q

IND405

What is the recommended Winter Indoor Design Condition?

[L3]

A

70°F dB & 20% to 30% RH

[L3]

36
Q

IND405

What is the Clothing Insulation range recommended for Winter & Summer?

[L3]

A
  • Winter = 0.8 to 0.9
  • Summer = 0.5 to 0.6

[L3]

37
Q

IND405

How much time is required per ASHRAE Standard 55 to define a space qualified for long term occupant use?

[L3]

A

A minimum of 15-minutes.

[L3]

38
Q

IND405

List the six (6) factors per ASHRAE 55 related to Thermal Comfort.

[L3]

A
  1. Metabolic Rate
  2. Clothing Insulation
  3. Air Temperature
  4. Radiant Temperature
  5. Air Speed
  6. Humidity

[L3]

39
Q

IND405

What is the formula for calculating a specific person’s metabolic rate per ASHRAE 55?

[L3]

A

[L3]

40
Q

IND405

True or False: The insulation factor of the clothing we wear everyday has a maximum limit of time to maintain our personal body temperature comfortably from the outdoor environment?

[L3]

A

True, it is calculated as the Tmax, lcl of clothing insulation

[L3]

41
Q

IND405

Is 65°F dB @ 50% RH inside or outside the Summer Comfort Range?

[L3]

A

Outside

[L3]

42
Q

IND405

What is the typical (°F) temperature range an office main lobby entrance is to save energy during the summer?

[L3]

A

4°F to 6°F

[L3]

43
Q

IND405

What is the minimum temperature (°F) allowed during the winter for a Garage per ASHRAE 55?

[L3]

A

40°F (dB)

[L3]

44
Q

IND405

What is the recommended design conditions all year around for hospital operating rooms per ASHRAE 55?

[L3]

A

72°F @ 55% RH

[L3]

45
Q

IND405

Are hospital operating rooms required to be positively, negatively, or neutrally pressurized facilities?

[L3]

A

Positively Pressurized

[L3]

46
Q

IND405

What are the two (2) temperature base references when calculating using Degree-Day method?

[L3]

A

65°F & 50°F

[L3]

47
Q

IND405

What is the HDD for just one (1) day when the outside temperature is 12°F for HDD50 & HDD65?

[L3]

A
  • HDD50 = 50°F - 12°F = 38°F
  • HDD65 = 65°F - 12°F = 53°F

[L3]

48
Q

IND405

What are the formulas for HDD & CDD?

[L3]

A
  • HDD = (Tbase – Ta) x No. Days
  • CDD = (Ta - Tbase) x No. Days

[L3]

49
Q

IND405

At what speed does the Wind Chill effect stop increasing?

[L3]

A

Any speed 43 mph or greater.

[L3]

50
Q

IND405

Are degree-days a unit of time? Yes or No.

[L3]

A

No, degree-days are a unit of time & temperature.

[L3]

HVAC Systems_FA23 (11 decks)

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